Hi Richard,
Thanks for reaching us on this issue. Let’s get more info about it.
Have you gone through the steps provided in our Testing for conflicts guide? The site you imported the events from has the same setup than the one you are importing to?
From what I see in the URL you provided this is happening in days where recurring events are present. Can you confirm this? Not sure if this is related with the other thread you point out, is the site on Multisite network too?
Thanks,
Nico